What is $90\%$ of $600$ ?
Solution: Having $90\%$ of something means that you get $90$ out of every $100$ We can set up a proportion to find out what number is $90\%$ of $600$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We know the ${\text{percent}}$ is $90$ . Is $600$ the ${\text{part}}$ or the ${\text{whole}}$ The $600$ is the ${\text{whole}}$ . We are trying to find the ${\text{part}}$ that makes up $90\%$ of it: $ \dfrac{{90}}{100} = \dfrac{{\text{part}}}{{600}}$ If we multiply the denominator of the fraction on the left by $6$ , it will be the same denominator of the fraction on the right. To keep things equal, let's also multiply the numerator on the left by $6$ $ \dfrac{{90} \times 6}{100 \times 6} = \dfrac{{\text{part}}}{{600}}$ $ \dfrac{{540}}{600} = \dfrac{{\text{part}}}{{600}}$ $ {540} = {\text{part}}$ So $540$ is $90\%$ of $600$.